Chapter one is an overview of TCP/IP. The material is generally good,
but does demonstrate a possible weakness of the book: we are provided
with way too much information about a number of areas that are not
relevant to IPSec. A similar overabundance of detail (and math)
describes symmetric cryptography, in chapter two. Oddly, given the
level of particulars in other areas, there is no analysis of the
weakness of double DES (Data Encryption Standard). Operational
specifics of the various AES (Advanced Encryption Standard) candidates
are also included. The mathematical basis of asymmetric cryptography,
in chapter three, is not explained as well as symmetric is. In
dealing with hashes and message authentication codes, chapter four has
lots of math and almost no other discussion. Chapter five provides
extensive details about X.509 attribute fields, for digital
certificates, and also has a bit of material on PGP (Pretty Good
Privacy) and key recovery. The fields of LDAP (Lightweight Directory
Access Protocol) are outlined in chapter six.

Chapter seven finally talks, very briefly, about IPSec architecture,
repeating (from chapter one) the specifics of the IP header, and
mentioning some of the components of IPSec. Chapters eight, nine, and
ten concentrate of the header structure of AH (Authentication Header),
ESP (Encapsulating Security Payload), and ISAKMP (Internet Security
Association Key Management Protocol) packets, albeit chapter ten also
covers a bit of the handshaking process. There is very little
discussion of strengths and weaknesses. There are lots of details
related to IKE (Internet Key Exchange) in chapter eleven, but
surprisingly little information about what it does or how it works.
The header structure and options for the compression function, IPComp,
are given in chapter twelve. Chapter thirteen is supposed to talk
about implementation, but has a fairly generic example of a VPN and
some screen shots from a commercial product.

Overall, the book contains lots of technical details, but very little
in the way of explanation, discussion, or analysis. You would
probably learn just as much about IPSec by reading the RFCs
themselves.